This invention relates to security apparatus and more particularly to apparatus for preventing unauthorized separation of a door from a cooperating buck assembly.
As is well known, many types of access doors in present usage are hinged or pivoted along one vertical edge to a cooperating rectangular frame commonly referred to as a door buck. The opposite vertical edge carries a spring biased latch within the door which protrudes into a mating opening in a strike plate on the buck assembly when the door is closed. The latch may be locked to secure the door in its closed position.
One of the ways of gaining unauthorized entry through a door which has been locked in this manner is to wedge a crowbar or similar burglar's tool between the door and the buck assembly and then pry the two apart. The door moves in its plane and becomes bowed sufficiently to carry the latch away from the strike plate by a distance equal to the latch's penetration in the strike plate opening. The door may then be readily moved to its open position.
Although attempts have been made heretofore to prevent such authorized entry through the use of interlocking plates and similar devices, these attempts have proved deficient in many respects. As an illustration, and this was of special moment in the mounting of the plates on a pre-existing door and buck installation, difficulties were encountered in positioning the plates in their proper locations. In addition, in several previous arrangements of this type the apparatus was deficient in providing the desired locking action with the necessary structural rigidity to do a really effective job. Further difficulties were encountered in arranging the interlocking plates such that they remained in position even after successive attempts to force the door.